In recent years, in terms of enhancing environmental performance or the like, attention has been focused on a vehicle in which the displacement of an internal combustion engine is reduced and which is equipped with a turbo-supercharger for reducing the decrease in output caused by the reduction of the displacement. In order to obtain, in such a vehicle, an acceleration feel of a vehicle equipped with a naturally-aspirated internal combustion engine of large displacement, it is necessary to increase supercharging efficiency to produce a high torque and to reduce a so-called turbo lag.
JP63-248973A discloses that, in a low supercharging region at the time of acceleration, ignition timing is subjected to correction of retarding, and thus the combustion state is brought into an afterburning state to increase the exhaust temperature, with the result that supercharging efficiency is enhanced.
JP2008-101502A discloses that control is performed into valve timing for obtaining a scavenging effect of blowing fresh air into an exhaust system, and an air-fuel ratio when the fresh air blown into the exhaust system is afterburned in the exhaust system is controlled such that the exhaust temperature resulting from the afterburning is the maximum, with the result that supercharging efficiency is enhanced.